When a fuel gas is supplied to a combustor, etc. in a gas turbine or the like, air and the fuel gas are previously uniformly mixed and injected in a mist form by a fuel injector.
As this fuel injector, a fuel injector that has a cylindrical shape to internally form a plenum and an inner baffle disposed such that a diameter thereof enlarges toward a downstream side is disclosed in, for example, Japanese Unexamined Patent Application, First Publication No. 2011-69602.
The fuel injector has upstream and downstream tube supports connected by an outer wall and is provided with a fuel injector body using an inner space as a plenum. In the fuel injector body, an inner baffle spreading toward an outer side in a radial direction to transverse the inner plenum in the radial direction is disposed. Further, a fuel delivery tube is connected to the fuel injector body from an upstream side thereof. The fuel injector body is provided with a plurality of premixing tubes that penetrate and fix the upstream tube support, the inner baffle, and the downstream tube support. In the premixing tubes, fuel injection holes for introducing a fuel gas are disposed upstream from the inner baffle in the plenum.
In the fuel injector having such a constitution, when the fuel gas is introduced into the plenum from a fuel delivery tube, the fuel gas flows toward the outer side in the radial direction along a downstream surface of the inner baffle to reach the vicinity of the outer wall. Afterwards, the fuel gas in the plenum flows toward the inner side in the radial direction along an upstream surface of the inner baffle while being introduced from the fuel injection holes of the premixing tubes disposed at an outer side in the radial direction. A cross-sectional area of the plenum is reduced toward the inner side in the radial direction. For this reason, a flow rate of the fuel gas in the plenum is gradually reduced toward the inner side in the radial direction. Thereby, in the fuel injection holes of the premixing tubes, a flow velocity of the fuel gas is constant, and an amount of supply of the fuel gas supplied to the premixing tubes is constant. Therefore, in the fuel injector, air supplied from the upstream sides of the premixing tubes and the fuel gas supplied from the fuel introduction holes can be uniformly mixed and injected regardless of positions at which the premixing tubes are disposed.